Devel::Events::Filter::Warn - log every event to STDERR

	# can be used as a handler
	my $h = Devel::Events::Filter::Warn->new();

	# or as a filter in a handler chain

	my $f = Devel::Events::Filter::Warn->new(
		handler => $sub_handler,
	);

This is a very simple debugging aid to see that your filter/handler chains are set up correctly.

A useful helper function you can define is something along the lines of:

	sub _warn_events ($) {
		my $handler = shift;
		Devel::Events::Filter::Warn->new( handler => $handler );
	}

and then prefix handlers which seem to not be getting their events with _warn_events in the source code.

filter_event @event

calls warn "@event". and returns the event unfiltered.